import tkinter as tk


window = tk.Tk()
window.title('my window')
window.geometry('200x200')

var = tk.StringVar()
l = tk.Label(window, bg='yellow', width=20)
l.pack()


def print_selection():
    l.config(text='you have selected  '+var.get())


r1 = tk.Radiobutton(window, text='Option A', variable=var,
                    value='A', command=print_selection)
r1.pack()
r2 = tk.Radiobutton(window, text='Option B', variable=var,
                    value='B', command=print_selection)
r2.pack()
r3 = tk.Radiobutton(window, text='Option C', variable=var,
                    value='C', command=print_selection)
r3.pack()

window.mainloop()
